This research proposal focuses on environmental risk factors associated with pediatric pneumonia, and will be nested within a large, CDC-funded, multi-center surveillance study of the incidence and etiology of community- acquired pneumonia (CAP) among hospitalized children and adults. The main objective of this proposal will be to understand the relationship between environmental tobacco smoke (ETS) exposure and pneumonia hospitalizations among young children in Middle Tennessee. The specific aims of the project are: 1. To objectively determine the extent of ETS exposure using biomarkers for nicotine in a cohort of young children hospitalized with pneumonia 2. To compare ETS exposure among children hospitalized with pneumonia with matched controls hospitalized with gastroenteritis 3. To correlate ETS exposure with clinical and functional disease severity among the hospitalized pneumonia cohort Previously published studies in adults demonstrate the prominent role that ETS has in the predisposition to and clinical severity of pneumonia. Thus, it is highly likely that a similar role of ETS can be established in young children. It is hypothesized that ETS exposure will be more common and more extensive among this group of young children hospitalized with pneumonia than among matched controls hospitalized with gastroenteritis. Furthermore, it is hypothesized that the extent of ETS exposure among young children hospitalized with pneumonia will impact clinical and functional disease severity, such that children with higher levels of ETS will require a longer time to achieve clinical stability and functional recovery. This work is unique and innovative because it measures actual biomarkers of ETS exposure in the urine of children hospitalized with pneumonia and gastroenteritis rather than simply relying on parental reports. If this work demonstrates a clear association between ETS exposure and pneumonia burden and disease severity, then these findings would impact environmental health policy efforts as well as smoking prevention and cessation strategies for caregivers. The long-term objective of this application is to foster a career in clinical investigation that centers on the epidemiologic surveillance of pediatric infectious diseases commonly leading to hospitalization and the important role that environmental factors have in disease burden. This proposal will greatly facilitate this career path by providing an intensive, mentored training experience with a highly qualified mentor that includes participation within a national, multicenter study and daily interaction with the study team, weekly and monthly research conferences, epidemiology coursework, and focused career development activities. PUBLIC HEALTH RELEVANCE: If this work establishes an important link between environmental tobacco smoke exposure (ETS) and childhood pneumonia burden and disease severity, it would add to the mounting evidence of the damaging effects of ETS on the respiratory health of children and would serve as an impetus for additional epidemiologic studies within this important area. Furthermore, it would inform health policy decisions such as comprehensive smoking bans in day care facilities and other public venues, and stimulate targeted smoking prevention and cessation strategies including hospital-based intervention programs for smoking parents.